Supersensitized silver halide photographic emulsion

ABSTRACT

A photographic silver halide emulsion containing (1) AT LEAST ONE SENSITIZING DYE HAVING THE GENERAL FORMULA (I)   wherein R, R1, R2 and R3 each is selected from the group consisting of an alkyl, a substituted alkyl, an allyl and an aralkyl group; wherein L is selected from the group consisting of a monomethine group and an aliphatic chain which may combine with the nitrogen atom in the heterocyclic nucleus containing Z1 to complete a heterocyclic ring; wherein R4 is selected from the group consisting of a hydrogen atom, an alkyl group, and an aryl group; wherein m, n and p each is 1 or 2, and d is 0, 1 or 2; wherein X is an anion; wherein Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus, and (2) AT LEAST ONE CONDENSATE OF FORMALDEHYDE WITH A POLYHYDROXYBENZENE SELECTED FROM THE GROUP OF COMPOUNDS HAVING THE GENERAL FORMULA (IIa), (IIb), (IIc)and (IId)   D R A W I N G

United States Patent 1' 3,650,762 Shiba et 1 Ma5- 212l?;7%

[5 SUPERSENSITIZED SILVER HALIDE aralkyl group; L is selected from the group con- PHOTOGRAPHIC EMULSION [72] Inventors: Keisuke Shiba; Masanao Hinata; Nobuo Tsuji; Takushi Miyazako; Akira Sato, all of Kanagawa, Japan [73] Assignee: Fuji Photo Film Co., Ltd., Ashigara- Kamigun, Kanagawa, Japan [22] Filed: July 14, 1970 [2]] Appl. No.: 54,852

[30] Foreign Application Priority Data July 14, 1969 Japan ..44/55'970 [52] U.S. CI ..96/122, 96/114, 96/123 [51] Int. Cl. ..G03c l/28, G03c 1/22 [58] Field ofSearch ..96/122,l14,115, 140,123

[56] References Cited UNITED STATES PATENTS Dawson et al. ..96/97 Primary ExaminerNorman G. Torchin Assistant Examiner-Alfonso T. Suro Pico Attorney-Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT A photographic silver halide emulsion containing l at leastone sensitizing dye having the general formula [I] sisting of a monomethine group and an aliphatic chain which may combine with the nitrogen atom in the heterocyclic nucleus containing Z, to complete a heterocyclic ring; wherein R is selected from the group consisting of a hy drogen atom, an alkyl group, and an aryl group; wherein ,m, n and p each is 1 or 2, and dis 0, 1 or 2; wherein X- is an anion; wherein Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus, and

(2) at least one condensate of formaldehyde with a polyhydroxybenzene selected from the group of compounds having the general formula [11a], [11b], [llcland [lld] sisting of -OH, -OM, OR NH NHR -N(R -NHNH and NHNHR in which R is selected from the group consisting of an alkyl group containing from one to eight carbon atoms, an aryl group and an aralkyl group; wherein M is selected from the group consisting of an alkali metal atom and an alkaline earth metal atom;

consisting of an alkyl, a substituted allcyl, anally] and an wherein X is selected from the group consisting of a hydroxyl group and a halogen atom; wherein X is a halogen atom; and wherein n n n and n each are l, 2 or 3, wherein n and n are not both 3 is disclosed 6 Claims, No Drawings BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to a silver halide photographic emulsion and, more particularly, to a supersensitized silver halide photographic emulsion.

2, Description of the Prior Art It is well known in the art of manufacturing silver halide photographic emulsions that the sensitive range of the spectrum of silver halide emsulsion can be expanded, namely, the emulsion can be optically sensitized by the addition thereto of a sensitizing dye.

When a silver halide emulsion is more intensively sensitized, in at least a portion of the spectral range sensitized by a sensitizing dye with the addition of the sensitizer in combination with a dye or other organic compound, which does not sensitize the emulsion in the same spectral range as the sensitizer, the silver halide emulsion is regarded as being supersensitizedu In this case, the compound which does not sensitize in the same spectral range as the sensitizer is referred to as a supersensitizer."

SUMMARY OF THE INVENTION We have discovered that supersensitization is achieved by the addition to a silver halide photographic emulsion ofa sensitizer dye represented by the following general formula 1, below, in combination with a novolak-type condensate of a substituted or unsubstituted polyhydroxybenzene with formaldehyde. The term polyhydroxybenzene" is intended to encompass substituted benzenes having from one to three hydroxy groups attached to the benzene nucleus. The novolalt-type condensate of a substituted or unsubstituted polyhydroxybenzene with formaldehyde is hereinafter referred to for convenience as the formalin condensate.

The sensitizer used with the formalin condensate has the general formula [I]:

azoles such as eight carbon atoms, an aryl group or an aralkyl group; M

represents an alkali or an alkaline earth metal atom; X represents a hydroxyl group or a halogen atom", 2; represents a halogen atom; and n, n n and it each represents l, 2 or 3, wherein n and n are not both 3.

DETAILED DESCRIPTION OF THE INVENTION R, R R and R in the general formula [I] can be, for example, methyl, ethyl, propyl, B-hydroxyethyl, B-acetoxyethyl. sulfatoethyl (-C H SO carboxymethyl. B-carboxyethyL y-carboxypropyl, ,B-sulfoethyl, 'y-sulfopropyl. 5-sulfobutyl. benzyl, phenethyl, p-carboxybenzyl, p-sulfophenethyl. phenyl or vinylmethyl groups.

R, in the general formula [I] can be, for example, a methyl, an ethyl or a phenyl group.

X in the general formula [I] can be, for example, a chlorine ion, a bromine ion, a perchlorate ion, a p-toluenesulfonate ion, a benzenesulfonate ion, an ethylsulfate ion or a methylsulfate ion.

Examples of the heterocyclic nuclei formed by Z or Z, in the general formula [I] are: thiazoles, such as thiazole itself and aryl-substituted thiazoles having a substituent on the nucleus such as, for example, a methyl or a phenyl group; benzothiazoles, such as benzothiazole itself and aryl-substituted benzothiazoles having a substituent on benzene nucleus such as, for example, a halogen atom, an alkyl, an alkoxy, or a phenyl group; naphthothiazoles, such as a naphthothiazole, B-napththothiazole, tetrahydronaphthothiazoles and substituted naphthothiazoles having on either of the benzene nuclei a substituent such as, for example, an alkoxy group; oxazoles such as oxazoles having on the nucleus a substituent such as, for example, an alkyl or a phenyl group; benzoxazoles such as benzoxazole itself and substituted benzoxazoles having on the benzene nucleus a substituent such as, for example, a halogen atom, a methyl, an ethyl, an ethoxy, a hydroxyl or a phenyl group; napththoxa-naphthoxazole or B-naphthoxazole; selenazoles such as 4-methylselenazole or 4-phenylselenazole;

wherein R, R,, R and R each represents an alkyl, a substituted alkyl, an ally or an aralkyl group; L represents a monomethine group or an aliphatic chain which may combine with the nitrogen atom in the heterocyclic ring to form a ring; R represents a hydrogen atom or an alkyl or an aryl group; m, n and p each is l or 2, and cl represents 0, l or 2; X represents an anion; and Z and Z, each represent the nonmetallic atomic group needed for forming a fiveor six-membered heterocyclic ring. Where p is 1 an intramolecular salt is formed.

The polyhydroxybenzene used in the present invention means such compounds as are represented by the following ge l. fQUJL JEE I l COR S OzRs 1)n of [mi] X; CH:

where, in these formulas R and R each represents OH, OM, -OR NH NHR N(R NHNH or NHNHR,,

benzoselenazoles such as benzoselenazole itself, 5- chlorobenzoselenazole, S-methylbenzoselenazole, S-methoxybenzoselenazole or 5-hydroxybenzoselenazole; naphthoselenazoles such as a-naphthoselenazole or B- naphthoselenazole; thiazolines such as thiazoline itself or 4- methylthiazoline; Z-quinolines such as quinoline itself and substituted quinolines having on either of the rings (except for 2-position) a substituent such as, for example, a halogen atom or a methyl, a methoxy or a hydroxy group; 4-quinolines such as quinoline itself and substituted quinolines having on either of the rings (except for the 4-position) a substituent such as, for example, a methyl or a methoxy group; benzimidazoles such as l,3-diethylbenzimidazole, l,3-diethyl-5- chlorobenzimidazole, or l,3-diethyl-5,6- dichlorobenzimidazole; 3,3'-dialkylindolenines such as 3,3- dimethyl-indolenine, 3,3,5-trimethylindolenine -trimethylindolenine or 3,3,7-trimethylindolenine; Z-pyridines such as pyridine itself and substituted pyridines having a substituent such as, for example, a methyl group, in other than the 2-position; and 4-pyridines.

Examples of the polyhydroxybenzens used in the present invention are: p-hydroxybenzene, o-dihydroxybenzene, ochlorophenol, m-chlorophenol, p-chlorophenol, obromophenol, m-bromophenol, p-bromophenol, 2,4- dichlorophenol, 2,6-dichlorophenol, 2,5-dichlorophenol, 2,4- dibromophenol, 2,5-dibromophenol, 2-chlorohydroquinone, 4-chlororesorcinol, 4-chlorocatechol, 2-bromohydroquinone,

in which 1 represents an alkyl group Containing from one to 75 4-bromoresorcinol, 4-bromocatechol, 2,4,5-trichlorophenol,

o-chloro-m-cresol, p-chloro-o-cresol and p-chloro-m-cresol. p-Hydroxybenzoic acid, p-hydroxybenzenesulfonic acid, hydroxybenzoic acid, o-hydroxybenzene-sulfonic acid, mhydroxybenzoic acid, m-hydroxybenzensulfonic acid, a-resorcinolic acid, B-resorcinolic acid, 'y-resorcinolic acid, 3,5- dihydroxybenzenesulfonic acid, 2,4-dihydroxybenzenesulfonic acid, 2,6-dihydroxybenzenesulfonic acid, 2,5-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,5-dihydroxybenzenesulfonic acid, pyrogallosulfonic acid(4), pyrogallolsulfonic acid(5), pyrogallolcarboxylic acid(4), pyrogallolcarboxylic acid(5) or gallic acid, and the alkali metal salts (Li, Na or K salts) and the alkaline earth metal salts (the Mg or Ca salts) thereof can also be used conveniently. In addition, the amides and hydrazides of such carboxylic acids and the sulfonic acids as mentioned above and the N-alkyl (containing from one to eight carbon atoms), the -aralkyl and the -aryl derivatives of the amides and hydrazides can also be used. Esters of such carboxylic acids and sulfonic acids can also be used.

The condensate of such substituted or unsubstituted polyhydroxy-benzenes with formaldehyde can by synthesized in the conventional process used for the synthesis of the novolak-type phenol-formaldehyde resins.

in general, a polyhydroxybenzene is dispersed in water and then a concentrated hydrochloric acid and a 37% formalin solution are added thereto. The mixture is stirred at 100 C. for from 30 minutes to 1 hour. The stirring is, if necessary, continued for an additional time after the addition of additional hydrochloric acid. On completion of the reaction, the mixture is poured into cold water and the resulting precipitate is recovered and purified.

Illustrating this process in greater detail, for instance, 415 parts of p-hydroxybenzoic acid is dispersed, with vigorous stirring. in 1,000 parts of water, then 25 parts of a 35% aqueous hydrochloric acid and 245 parts of a 35% formalin solution are added to the resulting dispersion. The reaction mixture is heated with stirring to 100 C. and stirred at this temperature for 30 minutes. parts of a concentrated hydrochloric acid is then added to the mixture and the stirring is continued. In the course of the reaction the reaction mixture becomes turbid. After about 1 and 30 minutes, the stirring is stopped and the reaction mixture is stirred into 3,000 parts of cold water. The resulting precipitate is recovered by filtration and, without drying, re-dissolved in methanol and reprecipitated with water. The precipitate is recovered by filtration and dried to obtain a product. The other substituted or unsubstituted polyhydroxybenzenes can be processed in a similar manner to obtain the corresponding novolak. The condensate thus obtained has, in general, a polymerization degree of from 2 to 10 similar to conventional novolak resins. if

The novolak-type condensate suitably used in the invention are those having a polymerization degree of from 2 to 10, preferably those having a polymerization degree of from 2 to 5 and having a molecular weight offrom 300 to 800.

The incorporation of the formalin condensate in combination with the sensitizer dye represented by the general formula [1] in a silver halide emulsion results in supersensitization and, according to circumstances, a remarkable reduction of fog in comparison with the incorporation of the sensitizer dye, represented by the general formula [1], alone. Although some of the sensitizing dyes represented by the general formula [I] have the disadvantage of reducing the sensitivity of an emulsion during storage when incorporated in a photosensitive material, the reduction ofthe sensitivity during storage can be minimized by incorporating the sensitizer in a emulsion in combination with the formalin condensate.

The sensitizing dye is used in an amount so as to provide a concentration offrom 0.002 to 0.2 g./g.-mol of silver halide in the emulsion and the formalin condensate is used in an amount so as to provide a concentration of from 0.1 to 5.0 g./g.-mol of silver halide. The preferred ratio ofthe concentration of the sensitizer to the concentration of the formalin condensate ranges from 1:5 to 1:500 by weight. Addition of the sensitizing dye to an emulsion can be performed in the manner as well known in the art. The formalin condensate can be added in solution in water or an organic solvent such as methanol, ethanol and the like to the emulsion. it is convenient to add the sensitizer and formalin condensate to an emulsion before the application of the emulsion to a base.

The sensitizer and the formalin condensate can be added in any order to the emulsion. They can be added in admixture to an emulsion. Alternately, they can be incorporated in an emulsion during aging of the emulsion following by washing with water.

While, in the practice of the present invention, an ordinary gelatin silver halide emulsion is conveniently used, other emulsions containing resinous materials or cellulose derivatives having no adverse effect on the photosensitive material can be used in place of the gelatin.

For preparation of the emulsions to be used in the present invention silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chloroiodobromide and like silver halides can be used.

The emulsion of the present invention can contain a chemical sensitizer, an anti-fogging agent, a stabilizer, a hardener. a coating assistant, a plasticizer, a developing promoter, a toner, a fluorescent, a bleaching agent, an air-fogging inhibitor, a coupler and other conventional additives. A dye for use in a silver-dye bleaching process as disclosed in Japanese Patent Specification No. 13093/ can also be incorporated in the emulsion.

The emulsion can be applied in a conventional manner to a suitable support, such as a sheet glass, a film of a cellulose derivative, a film of a synthetic resin, a laminated paper, a synthetic paper or a baryta paper.

The sensitizer of the general formula [1] for use in the present invention is exemplified by the following compounds but is not limited thereto.

The following examples are given to illustrate the present invention in greater detail but the present invention is not to be interpreted as being limited thereby.

EXAMPLES To separate portions of a silver halide emulsion from the same bath there was added l a sensitizer represented by the general formula [I] or (2) a combination of a sensitizer represented by the general formula ll] and a formalin condensate. Each portion of the emulsion thus sensitized was applied to an aeetylcellulose base. When the pH of the emulsion was lowered by addition thereto of the formalin condensate, the pH was adjusted by addition of an alkali. The coated film was, after drying, exposed through a FUJl filtervNo. 7 (transmitting light of wave lengths of about 590 millimicrons or above) or a FUJI filter No. 3 (transmitting light of wave lengths of about 480 millimicrons or above) and developed.

The value of the sensitivity is the relative value of the amount of exposure needed to give an optical density (including fog) of 0.] and was calculated by regarding the relative sensitivity of the emulsion containing the sensitizer alone to be I00. The values of such emulsions which contained no or little sensitization effect was obtained. Although in runs of the same examples an emulsion of the same batch was used, in the separate examples the same or different emulsions were used. The results are summarized in Table l. in Examples l to 4 a silver bromochloride of the same batch was used and in Examples 5 to l l a silver iodobromide of the same batch was used. Specimens in Example l3 were exposed only through a FUJI filter No. 3. The specimens in Examples 1 to 4 were developed at 20 C. for 2 minutes in the developing solution as indicated in the following Table 2, and the specimens in Examples 5 to l l were developed at 20 C. for 4 minutes in the developing solution as indicated in the following Table 3.

TABLE 1 Example Run 5 0. o. Additives tivity Fog 1 (a) I4(95.l) 1 0.07 (b) I-4(95.1) plus o-chlorophenol/FC (1400) 0.07 (c) I-4(95.l) plus p-chlorophenol/FC (1400) 186 0.06 (d) I4(95.1) plus p-bromophenol/FC (1400) 0.07 (e) I4(95.1) plus 2,4-dlchl0r0phenol/FC (1400) 126 0.07

2 (f) I-1(92.1) 100 0. 09 (g) I1(92.1) plus 2chlorohydroquinone/FC (1400). 126 0.09 (h) I1(92.l) plus 4-ch1or0resorcinol/FC (1400) 132 0.00 (i) I1(92.1) fiplus -chloro-m-cresol/FC (1400)." 132 0.09 (l) I1(92.1) plus fl-resorclnolic acld/FC (1400). 141 0.07 (k) I-1(02.1) plus y-resOrcinolic acid/F0 (1400) 155 0. 08

3 (l) I2(96.7) 100 0.10 (m) I2(96.7) plus 4-hydr0xybenzoic acid hydrazldel F0 (700)... 120 0.10 (n) I2(96.7) plus 3,5-dihydroxybenz0ic acid hydrazlde/FC (700) 120 0.10 (o) I2(96.7) plus hydroxybenzenesulfonlc acid/F0000) 126 0. 09 (p) I-2(96.7) plus p-hydroxybenzoic acid/FC (2800) 0.07 (q) I2(96.7) plus o-hydroxybenzoic acid/F0 (2800) 0.07

4 (r) I8(81.5) 100 0.10 (s) I8(81.5) plus o-hydroxybenzoic acid/F0 (2800) l 200 0.08 (t) I-8(81.5) plus m-hydroxybenzoie aeid/FC (2800) 220 0. 08 (u) I-8(81.5) plus p-dioxybenzene/FC (2800) 166 0. 10 (v) I8(8l.5) plus gallic acid/F0 (2800) 141 0. l0

5 (w) I3(97.0) 100 0.10 (x) I3(97.0) plus 0-hydroxybenzoic acid/F0 (2800) 130 0. 07

6 (y) I-5(B6.1) 100 0. 08 (z) I5(86.1) plus p-chlorophenol/FC (2800).. 126 0.07

7 V (a I-6(70.3) 100 0. 08 G1) I6(70.3) plus o-hydr0xybenzolc acid/F0 (2800) 141 0.08

8 (c I7(87.3) 100 0.07 (d I7(87.3) plus p-chlorophenol/FC (2800 130 0. 07

9 (e I9(74.0) 100 0.08 I9(74.0) plus 0-hydr0xybenzolc acid/FC (2800) 155 0.07

10 (g I10(84.6) 100 0. 11 (h) I10(84.6) plus p-hydroxybenzoie acid/F0 (1400) 204 0. 8

l1 (l I-1l(51.9) 100 0. 09 (l I11(5l.9) plus 0-hydr0xybenzoic acid/F0 (2800) 155 08 MgJg. moi of silver halide.

9 l TAPTE Z pounds having the general formulas [lla]. [llb]. [He] and [lld] N-rnethyl-p-aminophenol sulfate, g 3. 1 sodlum s g 01ml omnz 011 ,,3 Hydroqumone, g 12 Sodium carbonate (anhydrous), g 67. 5 Potassium bromide, g 1. 9 1 Diluted with water, 1 1

(80R, S OZRO (X0114 and 011 TABLE 3 [Ha] N-methyl-p-aminophenol sulfate, g 2. 2 Sodium sulfite, g 96 X, CH; Hydroquinone, g 8. 8 2 51 g 'l g 2 wherein R and R each is selected from the group consisting g f jg fi ffii j 1 or -on, -0 -oR1, NH2 -NHR,, -N RT 2. V NHNH and -NHNHR in which R, is selected from the group consisting of an alkyl group containing from one to eight carbon atoms, an aryl group and an aralkyl group; wherein M is selected from the group consisting of an alkali metal atom and an alkaline earth metal atom; wherein X, is selected from the group consisting of an hydroxyl group and a What is claimed is: halogen atom; wherein X is a halogen atom; and wherein n, l. A photographic silver halide emulsion containing n n and n each are l. 2 or 3, wherein n" and n are not both 1. at least one sensitizing dye having the general formula [I] 3.

Y 0 1'1: 0 1]: -Z------ 4 H R I\'T( CH=CH) b (=CH =C /C=L-C (=CHCH)m-t=N+ -Rl s s (x), 1

wherein R, R,, R and R each is selected from the group con- 2. An emulsion as claimed in claim 1, wherein the heterosisting of an alkyl, a substituted alkyl, an allyl and an aralkyl cyclic nucleus completed by Z or Z, is selected from the group group; wherein L is selected from the group consisting of a consisting of the thiazoles, benzothiazoles, naphthothiazoles, monomethine group and aliphatic chain which may combine oxazoles, benzoxazoles, naphthoxazoles, selenazoles, with the nitrogen atom in the heterocyclic nucleus containing benzoselenazoles, napthoselenazoles, thiazolines, Z-quin- Z, to complete a heterocyclic ring; wherein R is selected from 40 olines, 4-quinolines, benzimidazoles, 3,3'- dialkylindolenines, the group consisting of a hydrogen atom, an alkyl group, and 2-pyridines, and 4-pyridines. an aryl group; wherein m, n andpeach is 1 or 2, anda'is 0, l r 3. An emulsion as claimed in claim 1. wherein the sub- 2; wherein X is an anion; wherein Z and 2 each represents stituted alkyl group is selected from the group consisting of a the nonmetallic atoms necessary to complete a hetero-cyclic hydroxyalkyl, acetoxyalkyl, sulfatoalkyl, a carboxyalkyl. and a nucleus, and sulfoalkyl group.

4. An emulsion as claimed in claim 1. wherein the sensitizat least one condensate of fmmaldehyde 3 ing dye having the general formulalis selected from the group polyhydroxybenzene selected from the group of comconsisting f 0 C H 0 C H x i m H O I I C=CH&=C\ =C\ /=CH-C I H 0- 8 S \N Q O C H 0 C H 88 a '2 5 g [I I S -N N C=CH =CH-C I s s N 11m 2 i3 14 1-9 6, 5. An emulsion as claimed in claim I, wherein the amount 8 l S of said sensitizing dye ranges from 0.002 to 0.2 grams per gram mole of silver halide in the emulsion. wherein the C= =-CHC I amount of the condensate ranges front 0.] to 5.0 grams per 5 gram mole of silver halide in the emulsion. and wherein the 8 s N N weight ratio of the sensitizer dye to the condensate ranges J; from [:5 to 1:500 by weight.

zHa 2 6. A photographic light-sensltlve element comprising a sup- CH ort havin coated thereon at least one layer of the how- P 8 P v W H 10 graphic silver halide emulsion as claimed in claim 1.

O C H 0 C211 /8 A I I 5 g I I S l g l l C=CH-CH=CH-CH=C C=CH-'Q S aw! -15 C=CHCH=(IJ l \S/ \S/ 5H \N v 2 N/ 41H 6 

2. An emulsion as claimed in claim 1, wherein the heterocyclic nucleus completed by Z or Z1 is selected from the group consisting of the thiazoles, benzothiazoles, naphthothiazoles, oxazoles, benzoxazoles, naphthoxazoles, selenazoles, benzoselenazoles, napthoselenazoles, thiazolines, 2-quinolines, 4-quinolines, benzimidazoles, 3,3''-dialkylindolenines, 2-pyridines, and 4-pyridines.
 2. at least one condensate of formaldehyde with a polyhydroxybenzene selected from the group of compounds having the general formulas (IIa), (IIb), (IIc) and (IId)
 3. An emulsion as claimed in claim 1, wherein the substituted alkyl group is selected from the group consisting of a hydroxyalkyl, acetoxyalkyl, sulfatoalkyl, a carboxyalkyl, and a sulfoalkyl group.
 4. An emulsion as claimed in claim 1, wherein the sensitizing dye having the general formula I is selected from the group consisting of
 5. An emulsion as claimed in claim 1, wherein the amount of said sensitizing dye ranges from 0.002 to 0.2 grams per gram mole of silver halide in the emulsion, wherein the amount of the condensate ranges from 0.1 to 5.0 grams per gram mole of silver halide in the emulsion, and wherein the weight ratio of the sensitizer dye to the condensate ranges from 1:5 to 1:500 by weight.
 6. A photographic light-sensitive element comprising a support having coated thereon at least one layer of the photographic silver halide emulsion as claimed in claim
 1. 